Hello - I have ulcerative colitis, fibromyalgia, degenerative disc disease, Reynaud's...I got the first Pfizer dose in late February and I had a very high fever by the next morning and began experience my first POTs symptoms immediately thereafter. POTs symptoms continued. I had my second dose as appropriate in late March. POTs symptoms continued and got worse. After seeing my PCP and a cardiologist who both dx my with syncope, I went to the Cleveland Clinic Foundation and was diagnosed with POTs on June 16, 2021. The vaccine put me directly into a POTs, but perhaps I had POTs previously and it exacerbated my symptoms or I had COVID and did not know it and I developed POTs as others with COVID have experienced. I tell you this not to deter you from getting the vaccine, but to advise you to work closely with your doctors before deciding. Of course, it's been awhile since your post, so perhaps this information is too late.